Pakistan says an airstrike by the U.S.-led coalition in Afghanistan has killed 11 Pakistani security forces at a checkpoint near the Afghan border. VOA's Barry Newhouse reports that angry Pakistani officials are calling the incident an "unprovoked and cowardly act" against "the very basis" of Pakistan's cooperation in the war against terrorism.

Details about the incident are still unclear. U.S. military officials in Afghanistan released a statement saying U.S.-led coalition forces in Kunar province had been battling with insurgents just 200 meters inside Afghanistan's border. Lieutenant Nathan Perry said the operation had been previously coordinated with Pakistan

"While maintaining positive identification of the enemy, close air support was then used by coalition forces to gain fire superiority until the threat was eliminated," he said. "At no time did coalition ground forces cross into Pakistan. The investigation into this incident is ongoing."

There have been several border skirmishes reported in recent months between Afghan and Pakistani forces along the two countries rugged, unmarked border. But this appears to be the first incident that involved coalition airstrikes and reaction in the Pakistani government was swift.

The army condemned called the incident as "cowardly." Later, Prime Minister Yousuf Raza Gilani told the national assembly that the country has lodged a formal protest against the attack.

He says we have condemned it and we will not tolerate any action that threatens Pakistan's sovereignty.

Pakistan's foreign ministry later released a statement saying the attack was unprovoked and a violation of the international border between the two countries. The statement went on to say that the attack undermines the "very basis of our cooperation with the Coalition Forces."

A State Department spokesman said he had no details on what happened but could understand the Pakistani reaction. The spokesman said the loss of innocent life is obviously a tragedy and something we all try to avoid.

Pakistan's new government has been under international scrutiny for striking peace deals in regions of the country dominated by Pakistani Taliban forces. U.S. and NATO officials have said the deals will only help the Taliban launch attacks in Afghanistan and abroad.

A recent report by a U.S. research group released this week went even further in criticizing Pakistan, saying parts of the country's military and intelligence services are directly aiding Taliban forces in Afghanistan. The Rand Corporation report says that unless Pakistani support for the groups ends, the region's long-term security remains in jeopardy.

Pakistani officials rejected the allegation and called the report a "smear campaign" aimed at creating doubts about the country's commitment to supporting coalition forces in Afghanistan.